4N fastener puzzle

[PE9ZZ]

I'm looking for replacement screws for my Japanese-made Philips 22AH180 tuner. These are self-tapping Phillips pan head screws with 2.9 mm diameter and 1.1 mm thread pitch. They are similar to #3 screws but have narrower thread pitch because they are intended for use in metal. The manual lists 4Nx7 and 4Nx5.5 sizes. And 6Nx7 which is obviously larger, about 4 mm diameter. This suggests metric like M3. Which incidentally is also used in this tuner...

So the question is: which fastener type should I get that will fit?

 

[ryuuoh]

I'd probably go for the closest M size machine screw and use a tap on the sheet metal.
Also, screws get wrecked in old Japanese gear because Phillips and JIS screws are different.
https://www.vesseltools.com/handtools/screwdrivers/jis-japanese-industrial-standard

 

[PE9ZZ]

I'm not looking for a screwdriver, I'm looking for a screw. A fastener, if you will. Looks like the type I'm after is #4-24. 24 TPI is a thread pitch of about 1.1 mm, #4 is 2.9 mm in diameter. Let's find out if my local hardware store here in Amsterdam has something fitting. It might happen!

As for screwdriver, I found that Pozidriv PZ2 fits rather well in JIS screws. As always take care the screwdriver doesn't cam out. My Philips doesn't use JIS screws (no dot).

 

[Binkman]

self-tapping Phillips pan head screws with 2.9 mm diameter

In some cases depending on thickness of the metal.. I've reamed using a new screw and made formed a new thread i.e. if I can get the lead pitch to grab and get a turn on it I can back off and ream again, soft screws won't work alternative is a set of taps and even though you don't drill you can cut cross threads enough to hold.
Just an idea.

 

[PE9ZZ]

But that would be a last resort. When I got the tuner all original screws were gone and screws were used with the wrong thread. Fortunately the ham-fisted barbarian that damaged the threads of only five holes was also lazy. Not only left out 15 screws, he also didn't tighten them enough to cause serious damage. Fortunately I had the right screws in my tray and by carefully testing identified them.